The present invention relates to a telecommunication system for providing a call connection between a first subscriber station and a second subscriber station and a method for setting-up a call connection in a telecommunication system between a first subscriber station and a second subscriber station, wherein said first subscriber station is a mobile subscriber station, which is connected to a first mobile radio telecommunication network and said second subscriber station is connected to a telecommunication network connected to said first mobile radio telecommunication network, and switching means of a mobile telecommunication system for providing a call connection between a first subscriber station and a second subscriber station wherein said first subscriber station is a mobile subscriber station which is connected to a first mobile radio telecommunication network and said second subscriber station is connected to a telecommunication network which is connected to said first mobile radio telecommunication network.
FIG. 5 shows components of a typical digital cellular telecommunication system according to the standards of the global system for mobile communications GSM. Such a telecommunication system is usually divided into a switching sub-system NSS and a base station sub-system BSS. The switching sub-system NSS comprises a gateway mobile switching center GMSC, a home location register HLR and a plurality of visitor location registers VLRs and mobile switching centers MSCs. For the sake of clarity, only two mobile switching centers MSCs and one visitor location register VLR are depicted. The base station sub-system BSS is constituted by facilities such as radio transceivers and switching centers to link those radio transceivers. The network shown in FIG. 5 is simplified and details on the base station sub-system BSS are omitted for the sake of clarity. To link such a telecommunication system to another telecommunication system there is provided the gateway mobile switching center GMSC that serves to determine the MSC/VLR currently serving a mobile subscriber station MS in the telecommunication system and to route calls towards this mobile subscriber station MS.
To this end, the gateway mobile switching center GMSC is connected to the home location register HLR wherein subscriber information and mobile information to allow incoming calls to be routed to the mobile subscriber station MS are stored. Any administrative action by the network operator with respect to subscriber data is carried out in the home location register HLR.
As can be seen from FIG. 5, the GSM-network comprises a plurality of mobile switching centers MSC each covering a predetermined number of basic cells covering a service area in which a mobile subscriber station MS can move. To this end, each mobile switching center MSC is connected to a visitor location register VLR. When a roaming mobile subscriber station MS enters a service area assigned to a specific mobile switching center MSC, the mobile switching center MSC informs the associated visitor location register VLR about the presence of the mobile subscriber station MS.
To route a call to a mobile subscriber station MS, the gateway mobile switching center GMSC is also connected to the mobile switching center MSC through which the mobile subscriber station MS can obtain a service. The mobile switching center MSC performs the necessary switching functions required for mobile subscriber stations MS covered by this mobile switching center MSC. In particular, the mobile switching center MSC monitors the mobility of its mobile subscriber stations MS and manages necessary resources required to handle and update the location registration updating procedures. Location information concerning the respective mobile subscriber stations MS is available in said mobile switching center MSC and is stored in said visitor location register VLR. The home location register always contains the address of the visitor location register VLR or the mobile switching center assigned to the cell in which the respective mobile subscriber station MS is currently located. If said mobile subscriber station MS is located in another GSM network which is not its home-GSM network, the home location register HLR in the home-GSM network of the mobile subscriber station MS contains an address of said other GSM-network pointing to an HLR of the other network.
The base station sub-system BSS corresponds to a physical equipment providing radio coverage to prescribed geographical areas referred to as cells and shown as hexagonal geographical regions in FIG. 5. Each base station sub-system BSS contains equipment required to communicate with the mobile subscriber stations MS such as a plurality of switching centers (not shown). Functionally, the base station sub-system BSS provides a control function carried out by a base station controller BSC and a transmitting function performed by the base transceiver system BTS (both not shown) The base transceiver system BTS corresponds to a radio transmission equipment that covers each cell. A base station sub-system can serve several cells because it can have multiple base transceiver systems BTS.
In a conventional GSM network as shown in FIG. 5 and operating as described above, there is available network information indicating a current location of a mobile subscriber station MS. However, said network information is kept inside the GSM network.
WO 96/25830 discloses a conventional telecommunication system. For determining a position of a mobile subscriber station in a mobile radio telecommunication network in said telecommunication system, the telecommunication system establishes a call connection generated by a position handler. Such a call connection for the determination of the position of a mobile subscriber station is referred to as a simulated call connection. In the simulated call connection, a call connection is established between the position handler and the mobile subscriber station in question. Therefore, a radio path has to be established between the mobile subscriber station in question and the nearest or best suitable Base Transceiver Station serving the area in which the mobile subscriber station in question is momentarily located. The position handler contains mobile subscriber station categories and subscriber stations intended for simulated call connections. The simulated call connection is released when the system has sent a paging message to said mobile station and after said mobile subscriber station has sent a response to this paging message. This response is used to determine the cell in which the mobile subscsriber station is located. A so-called timing advance of a mobile subscriber station can be used to obtain more accurate positioning of said mobile subscriber station in the cell.
U.S. Pat. No. 5,625,668 discloses another conventional telecommunication system providing a polling system to determine the location of a mobile subscriber station. A calling subscriber who requests location information on a mobile subscriber station firstly accesses a database processing facility. This database processing facility accesses the mobile subscriber station through the nearest cellular station. A radio path has to be established between the nearest cellular station and the mobile subscriber station. Then, a current location of the mobile subscriber station is determined by means of a global positioning system GPS arranged in said mobile subscriber station. The location information thereby obtained in transmitted via said radio path to the nearest cellular station and further to said database processing facility which forwards said location information to the requesting subscriber station.
In both conventional telecommunication systems respectively disclosed in WO 96/25830 and U.S. Pat. No. 5,625,668 it is necessary to access the mobile subscriber station in the mobile radio telecommunication network. Accordingly, each time a requesting subscriber station requests location information of a mobile subscriber station, a radio path has to be established between the nearest cellular station and the respective mobile subscriber station in question causing a high signaling load on the radio path. Accordingly, a request for location information concerning a mobile subscriber station has the same resource consumption as a call connection. The term xe2x80x9cresource consumptionsxe2x80x9d relates to the occupation, i.e. the use of means which are necessary to establish a call connection to a mobile subscriber station in a mobile radio telecommunication network. Since the number of radio paths in one cell is limited, the number of calls handled simultaneously in one cell is limited. The number of actual calls handled in a cell at the same time is reduced by the number of requests for location information of mobile subscriber stations in said cell.
In view of the above-described disadvantages, it is the object of the present invention to minimize the consumption of resources in the network.
This object is solved by a telecommunication system for providing a call between a first subscriber station and a second subscriber station wherein said first subscriber station is a mobile subscriber station which is connected to a first mobile radio telecommunication network, comprising location information extracting means for extracting location information indicating a current location of said first mobile subscriber station in said first mobile radio telecommunication network from network information available in said first mobile radio telecommunication network and location information providing means for providing said location information to said second subscriber station in response to a request requesting said location information.
Thus, the advantage is that the request for location information concerning a mobile subscriber station does not occupy network resources.
In an embodiment of the present invention said second subscriber station is connected to said first mobile radio telecommunication network or a switched telephone network connected to said first mobile radio telecommunication network or a second mobile radio telecommunication network connected to said first mobile radio telecommunication network.
A further embodiment of the present invention comprises blocking means for disabling said location information providing means from providing said location information of said first subscriber station to said second subscriber station.
A further embodiment of the present invention comprises geographical area determining means for determining whether said first subscriber station is located within a predetermined geographical area.
A further embodiment of the present invention comprises routing means for routing a call set-up request to said first subscriber station based on the determining result from said geographical area determining means to set-up a call between said first subscriber station and said second subscriber station.
In a further embodiment of the present invention said first and second mobile radio telecommunication network are part of a global system for mobile communication GSM and said switched telephone network is an integrated services digital network ISDN or any other data network.
In a further embodiment of the present invention said network information available in said first mobile radio telecommunication network indicates a location of a switching center of said first mobile radio telecommunication network or a data base associated with said switching center or a radio cell in which said first subscriber station is located.
A further embodiment of the present invention comprises location information translating means for translating said location information into geographical information.
In a further embodiment of the present invention said information location translating means is adapted to translate said location information into full text or into a map of a relevant geographical area indicating said current location of that first subscriber station.
The object of the present invention is further solved by a method for setting-up a call in a telecommunication system between a first subscriber station and a second subscriber station, wherein said first subscriber station is a mobile subscriber station which is connected to a first mobile radio telecommunication network, comprising the steps of receiving a request for obtaining location information concerning said first subscriber station from said second subscriber station, extracting location information indicating a current location of said first subscriber station from network information available in said first mobile radio telecommunication network and providing said extracted location information to said second subscriber station.
An embodiment of the inventive method further comprises a step of determining whether said first subscriber station is located within a predetermined geographical area based on said location information, and setting-up a call between said first subscriber station and said second subscriber station if said mobile subscriber station is within said predetermined geographical area.
A further embodiment of the inventive method comprises a step of disabling the provision of said location information to said second subscriber station.
A further embodiment of the inventive method comprises the step of translating said location information into geographical information.
The object of the present invention is further solved by switching means of a mobile telecommunication system for providing a call between a first subscriber station and a second subscriber station wherein said first subscriber station is a mobile subscriber station which is connected to a first mobile radio telecommunication network, comprising location information extracting means for extracting location information indicating a current location of said first subscriber station in said first mobile radio telecommunication network from network information available in said first mobile radio telecommunication network and location information providing means for providing said location information concerning said first subscriber station to said second subscriber station in response to a request requesting said location information.
In an embodiment of the inventive switching means said second subscriber station is connected to said first mobile radio telecommunication network or a switched telephone network connected to said first mobile radio telecommunication network or a second mobile radio telecommunication network connected to said first mobile radio telecommunication network.
A further embodiment of the inventive switching means comprises blocking means for disabling said location information providing means from providing said location information of said first subscriber station to said second subscriber station.
A further embodiment of the inventive switching means comprises geographical area determining means for determining whether said first subscriber station is located within a predetermined geographical area.
A further embodiment of the inventive switching means comprises a routing means for routing a call set-up request to said first subscriber station based on the determining result from said geographical area determining means to set-up a call between said first subscriber station and said second subscriber station.
In a further embodiment of the inventive switching means said first and second mobile radio telecommunication networks are a part of a global system for mobile communications GSM and said switched telephone network is an integrated services digital network ISDN or any other data network.
In a further embodiment of the inventive switching means said network information available in said first mobile radio telecommunication network indicates a location of a switching center of said first mobile radio telecommunication network or a database associated with said switching center or a radio cell in which said first subscriber station is located.
In a further embodiment said inventive switching means comprises location information translating means for translating said location information into geographical information.
In a further embodiment of the inventive switching means, said information location translating means is translating said location information into full text or into a map of a relevant geographical area indicating said current location of said first subscriber station.
In a further embodiment said inventive switching means is a gateway mobile switching center GMSC in a GSM network.
Further advantageous embodiments and improvements of the invention become apparent from the dependent claims.